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(4) Areas of very low rainfall : The areas getting less than 60 cm rainfall are termed as the very
low rainfall areas. Desert areas of Rajasthan and Gujarat, Ladakh region of Jammu and
Kashmir and Leeward side of the western Ghats get less than 60 cm rainfall.
Impacts of uneven rainfall :
(1) Areas receiving high rainfall are affected by floods.
(2) Areas of low rainfall are drought prone in India.
Q4. How Himalayas play a vital role in formulating the climate of India?
Ans. (1) The Himalayas have played a vital role to shape and influence the climate of India.
(2) The Himalayas are responsible for the Tundra type of climate in the upper parts of Jammu
and Kashmir, Himachal Pradesh etc.
(3) The Himalayas intercept the South-West monsoon and cause rainfall in the northern India.
(4) They prevent the cold winds of central Asia from penetrating into India. India would have
been a cold desert without the Himalayas.
(5) The Himalayas are also responsible for dividing the jet stream into two branches.
(6) The Himalayas check the monsoon winds and do not allow them to cross otherwise the North
India would have been a desert.
(7) The Himalayas have shaped the climate of the Northern India.
Q5. Distinguish between windward side and leeward side.
Ans. Windward side
(1) The area or the side of a mountain which gets more rain is called the windward side.
(2) It receives more rain because it is front side of the mountain.
(3) Mumbai is on the windward side. Hence gets heavy rainfall.
Leeward side
(1) The sloped side of a mountain which is dry and gets less rain is called the leeward side.
(2) It is dryer because when the clouds climb the mountains, they lose most of its water. So, this
part remains dry.
(3) Pune is on the leeward side. Hence gets the less rainfall.
D. NCERT TEXTBOOK QUESTIONS WITH ANSWERS
Q1. Choose the correct answer from the four alternatives given below.
(i)
Which one the following places receives the highest rainfall in the world ?
(a)
Silchar
(b) Mawsynram
(c)
Cherrapunji
(d) Guwahati
Ans. (b) Mawsynram.
(ii) The wind blowing in the northern plains in summers is known as :
Ans.
(a)
Kaal Baisakhi
(b) Loo
(c)
Trade Winds
(d) None of the above
(b)
Loo.
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(iii) Which one of the following causes rainfall during winters in north-western part of India.
Ans.
(a) Cyclonic depression
(b) Retreating monsoon
(c) Western disturbances
(d) Southwest monsoon
(c) Western disturbances.
(iv) Monsoon arrives in India approximately in :
Ans.
(a) Early May
(b) Early July
(c) Early June
(d) Early August
(c) Early June.
(v) Which one of the following characterises is the cold weather season in India ?
Ans.
(a) Warm days and warm nights
(b) Warm days and cold nights
(c) Cool days and cold nights
(d) Cold days and warm nights
(c) Cool days and cold nights.
Q2. Answer the following questions briefly.
(i)
What are the controls affecting the climate of India ?
Ans. There are six major controls affecting the climate of India.
(a) Latitude
(b) Altitude
(c) Pressure and wind system
(d) Distance from the sea
(e) Ocean currents
(f)
Relief features
(ii) Why does India have a monsoon type of climate?
Ans. India is having monsoon type of climate. Monsoon is Arabic word which means ‘mausim’ or
season. The monsoon winds bring rainfall in the Indian subcontinent and it remains active from
early June to October. Around 90 % of the Indian rainfall is caused by the monsoon winds.
Therefore, Indian climate is called the monsoon type of climate.
(iii) Which part of India does experience the highest diurnal range of temperature and why ?
Ans. Diurnal range of temperature means difference in temperature of a place in a single day. Indian
desert is the highest diurnal range of temperature. Temperature in the desert may be as high as
50°C in a day and as low as 15°C in the night. The desert area has extreme type of climate and
arid region causes the difference in the day night temperature. Sand becomes very hot in the day
and cools down rapidly in the night. Therefore, the Indian desert has the highest diurnal range of
temperature.
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(iv) Which winds account for rainfall along the Malabar coast ?
Ans. The Southern part of the western coast is known as the Malabar coast. The Arabian Sea branch of
the South-West monsoon strike the Malabar coast and bring rainfall.
(v) What are jet streams and how do they affect the climate of India ?
Ans. Jet streams are the fast blowing winds in a narrow belt in the troposphere. In India, Jet streams
blow south of the Himalayas. The jet streams are located over 27° to 30° N latitude. Hence also
called subtropical westerly jet streams. Jet streams help in the sudden burst of the monsoon. Jet
streams bring storms, rain and thunder in a short span of time.
(vi)
Define monsoons. What do you understand by "break" in monsoon ?
Ans. The word Monsoon is derived from the Arabic word ‘Mausim’ which means season. The winds
which bring rainfall in India and change their direction with change in season are called the
monsoon winds.
Break in Monsoon : During the rainy season, there are certain periods when the monsoon
becomes weak, the rain decreases and there are rainless intervals. This is called ‘break in
monsoon'. The normal break period is around seven days but sometimes it may be longer.
(vii) Why is the monsoon considered a unifying bond ?
Ans. (a)
Monsoon influence the climate of the North India and enables the uniformity in the climate.
(b)
The seasonal change of the monsoon winds provide rhythmic cycle of seasons.
(c)
The Indian agriculture mainly depend upon the monsoon gamble. The agriculture calendar
is based upon the monsoon.
(d)
The Indian vegetation and wild life depend on the monsoon.
(e)
Many Indian cultural and festival events are associated with the monsoon.
(f)
Thus, the monsoon winds are eagerly awaited in Indian and act like a unifying bond.
Q3. Why does the rainfall decrease from the east to the west in northern India ?
Ans. The rainfall decrease from the east to the west in Northern India. In summer, the monsoons rise
both from the Bay of Bengal and the Arabian Sea. The Bay of Bengal branch of monsoon cause
heavy rainfall in North-Eastern parts i.e. the Brahmaputra Valley and the Assam Hills (i.e. in
Cherrapunji). Because of the Himalayas they then take a western turn and move up the Ganga
Valley but as they move westwards they become drier. Hence, they cause less rain as they move
forward. Rainfall in the Ganga valley decreases from the east to the west.
Q4. Give reasons as to why ?
(i)
Seasonal reversal of wind direction takes place over the Indian subcontinent?
Ans. During summer, ocean is colder than land, because it cannot warm up so quickly, while land
warms up quickly, and air above land expands, leading to winds directed toward ocean.
Therefore, areas of low pressure develop in north and northwest parts of India due to which
winds from the high pressure area i.e. sea begin to blow towards the land masses.
During winter season, it is opposite, land cools down much faster, air contracts, leading to winds
from ocean. Hence, monsoon winds blow from northeast India towards the sea during winter
(November to April). During winter (October - November) with the apparent movement of sun
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towards the south, the low pressure trough over the northern plains becomes weaker which
causes the monsoon wind to blow from northeast to south during this period.
Therefore, a shift in the development of monsoon trough or low pressure belt along with the
change of season is the main reason for the reversal of wind direction in Indian subcontinent.
(ii)
The bulk of rainfall in India is concentrated over a few months.
Ans. The bulk of rainfall in India is concentrated over a few months starting from June to September.
During these four months, the rain-bearing winds called the South-West Monsoons, blow
northwards in two branches from the Arabian Sea and the Bay of Bengal. These winds blow from
the oceanic high pressure areas towards the low pressure areas of land and make a heavy
rainfall. Winds blowing from the Arabian Sea cause heavy rainfall exceeding 300 cm along the
Western Ghats. Winds blowing from the Bay of Bengal cause heavy rainfall in the hills of Assam,
Meghalaya, Mawsynram.
(iii)
The Tamil Nadu coast receives winter rainfall.
Ans. In winter there is a high pressure on the Indian mainland while the pressure over the Indian
Ocean remains low. So, winds start blowing from Indian mainland towards the sea in winter.
These winds are called retreating monsoons which blow in the months of October and November
from the land towards the sea from northeast direction. When these dry winds cross over the Bay
of Bengal, they pick up moisture and when they strike against the Eastern Ghats they cause
heavy rain on the east coast of India. Hence, southern part of east coast of India or the Tamil
Nadu coast receives more rain during the winter months from October to November.
(iv)
The delta region of the eastern coast is frequently struck by cyclones.
Ans. In India a gradual climatic transition from hot rainy season to dry winter season takes place
during the months of October and November. In the second half of October, temperature starts
falling rapidly especially in North India and the low pressure conditions starts shifting towards
the Bay of Bengal by November. This shift causes cyclonic depression in the Andaman Sea. These
tropical cyclones cause heavy and wide-spread rains on the Eastern Coasts of India. So they often
become destructive and the densely populated deltas of the Godavari, the Krishna, the Kaveri
are frequently struck by these cyclones causing heavy damage to life and property every year.
(v)
Parts of Rajasthan, Gujarat and the leeward side of the Western Ghats are drought-prone.
Ans. Drought in Rajasthan and Gujarat: There is often low rain in Rajasthan (Thar Desert) and
Gujarat because there is no relief or obstruction here to check the monsoons coming from the
Arabian Sea. The Aravalli Hills lie parallel to the direction of the monsoons as such the
monsoons bypass Rajasthan and Gujarat unobstructed and so, without giving any rain.
Moreover, in the summer the temperature of the Thar Dessert or Western Rajasthan is so high
that the monsoon winds that pass over this region get dried and unable to cause any rain.
Drought in the Leeward side of Western Ghats: There is often low rainfall in the Leeward side of
Western Ghats because that area comes under the rain shadow area.
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Q5. Describe the regional variations in the climatic conditions of India with the help of suitable
examples.
Ans. The climate of India is described as that of the monsoon type. But within this general pattern
there are found certain regional variations in climatic conditions. This is because of the
variations in temperature, precipitation, atmospheric pressure, wind, humidity and altitude from
place to place. Following are a few examples which prove the above fact:
(a) Range of Temperature : Temperature has great bearing on the climate, so difference in
temperature is bound to create variation in the climate. In India there are places like,
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Rajasthan and south-west Punjab, where the mercury rises even up to 55 C. On the other
hand, there are places like Drass, near Kargil, where the temperature sometimes, touches as
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low as -45 C.
(b) Direction of the Rain-bearing Winds : The direction of the Rain-bearing winds has a great
impact on the climate of a place. The summer monsoons arising from the Arabian Sea
because of their south-west direction strike the Western Ghats first and cause a heavy
rainfall there (about 250 cm). But these winds reach the Eastern Ghats last of all so there is
less rainfall in Tamil Nadu and consequently it is much lower as compared to the rainfall on
the Malabar Coast of the Western Ghats.
(c) Form of Precipitation : The form of precipitation whether it is in the form of light rains or
heavy snow has also a great-bearing on the climate of an area. In winter north-west of India
gets some rains due to the Western Disturbances. As a result, there is little rain in the plains
of Punjab and Haryana but there is heavy snowfall in the Western Himalayas especially in
Himachal Pradesh and Jammu and Kashmir. It is all due to the change in the form of
precipitation.
(d) Amount of Rainfall : Difference in rainfall is bound to create variations in climate. In India,
there are places like Mawsynram which receives 1,080 cm of rainfall annually. This is
perhaps the highest rainfall all over the world. On the other hand, there are places in India,
especially in Rajasthan, which gets 20 cm of annual rainfall.
(e) Rainfall regime or Seasonal distribution of rainfall : In India, there are many parts which get
rainfall only in summer while there are others which remain dry in that season. On the other
hand, there are certain places which get rainfall in winter alone while there are others which
get scanty or no rainfall in winter. For example, Tamil Nadu and AP get much of their
rainfall in winter season, and in summer they are almost dry. This seasonal distribution of
rainfall has a great bearing on climate. In summer, both Tamil Nadu and AP experience dry
and hot season while the rest of the country especially Kerala, Karnataka and Maharashtra
on the west-coast of India has a pleasant climate.
Q6. Discuss the mechanism of monsoons.
Ans. The word ‘monsoon’ stands for the seasonal reversal in the wind direction during a year. The
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monsoon winds are confined to the tropical area lying between 20 N to 20 S latitudes. The
mechanism of monsoons or the phenomena of the seasonal reversal in wind direction is related to
the fact given ahead.
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(1) The differential heating and cooling of land and water.
(2) The shift of the position of Inter Tropical Convergence Zone (ITCZ) in summer over the
Ganga plain.
(3) The presence of high pressure area, east of Madagascar over the Indian Ocean. The intensity
and position of this high pressure area affects the Indian monsoon.
(4) The Tibetan plateaus gets intensely heated during summer resulting into strong vertical air
currents and the information of low pressure over the plateau.
(5) The movement of the westerly jet stream to the north of the Himalayas and the presence of
the tropical easterly jet stream over the Indian Peninsula during summer.
The meteorologists have found out a seesaw kind of relationship between the meteorological
changes going on over the Pacific and the Indian Ocean. Whenever there is high pressure in the
subtropical region of the Pacific Ocean in the northern hemisphere, the pressure in the south of
Indian Ocean tends to be low and vice-versa. This is known as the 'Southern Oscillation' or SO
which causes the shifting of winds across the equator in different directions. Besides the above
facts, some other events such as E1 Nino, ENSO etc., are also connected to the mechanism of
monsoons.
Q7. Give an account of weather conditions and characteristics of the cold season.
Ans. The cold weather persists from December to February throughout India. January is the coldest
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month in the northern parts of India. During this period temperature varies from 10 C to 15 C in
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northern plains and 25 C in southern parts of the country. There is high pressure in northern
plains due to the cold climatic conditions. The cold dry winds blow from the high pressure
towards the low pressure equatorial regions. These winds are north-westerly in the Ganga plains
and north-easterly over the Bay of Bengal. Only two parts of the country receive rain in this
season. First is the north-west part of the country which receives rainfall, caused by the Western
Cyclonic Disturbances originating in the Persian Gulf and Mediterranean regions. Second is the
coast of Tamil Nadu which gets rainfall in winter because of the north-east winds on Retreating
Monsoons which blow over the Bay of Bengal. But in other parts of the country, the weather is
pleasant with clear skies and bright sunshine.
Q8. Give the characteristics and effects of the monsoon rainfall in India.
Ans. Following are the main characteristics of the monsoon rainfall in India:
(a) The monsoons account for 90% of the rainfall received by India. Almost every part of the
country except the east coast of Tamil Nadu receives the bulk of rainfall from the summer
monsoons or advancing monsoons.
(b) A low pressure near the Himalayas may result in heavy rains in the hills causing floods in
the plains or the plains may face prolonged dry spells.
(c) Overall rainfall is not the same every year. The monsoons may be strong or weak in a
particular year depending on the intensity and frequency of depression in the Bay of Bengal.
(d) The monsoon rains are not evenly distributed. The rainfall is neither continuous nor regular
even in the wettest areas.
(e) Sometimes, the monsoons may break too early or too late. There may be too long or too many
breaks in the monsoons, which may retreat too early or too late. All these factors upset the
agricultural operations making agriculture in India a mere gamble.
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